Multi-Bit Binary Input Direct Record (mbbiDirect)

The mbbiDirect record retrieves a 32-bit hardware value and converts it to an array of 32 unsigned characters, each representing a bit of the word. These fields (B0-B9, BA-BF, B10-B19, B1A-B1F) are set to 1 if the corresponding bit is set, and 0 if not.

This record's operation is similar to that of the multi-bit binary input record, and it has many fields in common with it. This record also has two available soft device support modules: Soft Channel and Raw Soft Channel.

Parameter Fields

The record-specific fields are described below, grouped by functionality.

Scan Parameters

The mbbiDirect record has the standard fields for specifying under what circumstances the record will be processed. These fields are listed in Scan Fields.

Read and Convert Parameters

The device support routines obtain the record's input from the device or link specified in the INP field. For records that obtain their input from devices, the INP field must contain the address of the I/O card, and the DTYP field must specify the proper device support module. Be aware that the address format differs according to the I/O bus used.

Two soft device support modules can be specified in DTYP Soft Channel and Raw Soft Channel.

Raw Soft Channel reads the value into RVAL, upon which the normal conversion process is undergone. Soft Channel reads any unsigned integer directly into VAL. For a soft mbbiDirect record, the INP field can be a constant, a database, or a channel access link. If INP is a constant, then the VAL is initialized to the INP value but can be changed at run-time via dbPutField or dbPutLink.

For records that don't use Soft Channel device support, RVAL is used to determine VAL as follows:

1. RVAL is assigned to a temporary variable rval = RVAL
2. rval is shifted right SHFT number of bits.
3. VAL is set equal to rval.

Each of the fields, B0-BF and B10-B1F, represents one bit of the word.

FieldSummaryTypeDCT DefaultReadWriteCA PP
VALCurrent ValueLONGYes YesYesYes
INPInput SpecificationINLINKYes YesYesNo
RVALRaw ValueULONGNo YesYesYes
B0Bit 0UCHARNo YesYesYes
B1Bit 1UCHARNo YesYesYes
B2Bit 2UCHARNo YesYesYes
B3Bit 3UCHARNo YesYesYes
B4Bit 4UCHARNo YesYesYes
B5Bit 5UCHARNo YesYesYes
B6Bit 6UCHARNo YesYesYes
B7Bit 7UCHARNo YesYesYes
B8Bit 8UCHARNo YesYesYes
B9Bit 9UCHARNo YesYesYes
BABit 10UCHARNo YesYesYes
BBBit 11UCHARNo YesYesYes
BCBit 12UCHARNo YesYesYes
BDBit 13UCHARNo YesYesYes
BEBit 14UCHARNo YesYesYes
BFBit 15UCHARNo YesYesYes
B10Bit 16UCHARNo YesYesYes
B11Bit 17UCHARNo YesYesYes
B12Bit 18UCHARNo YesYesYes
B13Bit 19UCHARNo YesYesYes
B14Bit 20UCHARNo YesYesYes
B15Bit 21UCHARNo YesYesYes
B16Bit 22UCHARNo YesYesYes
B17Bit 23UCHARNo YesYesYes
B18Bit 24UCHARNo YesYesYes
B19Bit 25UCHARNo YesYesYes
B1ABit 26UCHARNo YesYesYes
B1BBit 27UCHARNo YesYesYes
B1CBit 28UCHARNo YesYesYes
B1DBit 29UCHARNo YesYesYes
B1EBit 30UCHARNo YesYesYes
B1FBit 31UCHARNo YesYesYes

Operator Display Parameters

These parameters are used to present meaningful data to the operator.

See Fields Common to All Record Types for more on the record name (NAME) and description (DESC) fields.

FieldSummaryTypeDCT DefaultReadWriteCA PP
NAMERecord NameSTRING [61]No YesNoNo
DESCDescriptorSTRING [41]Yes YesYesNo

Run-time Parameters

These parameters are used by the run-time code for processing the mbbi direct record. They are not configurable prior to run-time.

MASK is used by device support routine to read hardware register. Record support sets low order NOBT bits in MASK. Device support can shift this value.

MLST holds the value when the last monitor for value change was triggered.

FieldSummaryTypeDCT DefaultReadWriteCA PP
NOBTNumber of BitsSHORTYes YesNoNo
ORAWPrev Raw ValueULONGNo YesNoNo
MASKHardware MaskULONGNo YesNoNo
MLSTLast Value MonitoredLONGNo YesNoNo

Simulation Mode Parameters

The following fields are used to operate the record in simulation mode.

If SIMM (fetched through SIML) is YES or RAW, the record is put in SIMS severity and the value is fetched through SIOL (buffered in SVAL). If SIMM is YES, SVAL is written to VAL without conversion, if SIMM is RAW, SVAL is trancated to RVAL and converted. SSCN sets a different SCAN mechanism to use in simulation mode. SDLY sets a delay (in sec) that is used for asynchronous simulation processing.

See Input Simulation Fields for more information on simulation mode and its fields.

FieldSummaryTypeDCT DefaultReadWriteCA PP
SIMLSimulation Mode LinkINLINKYes YesYesNo
SIMMSimulation ModeMENU (menuSimm)No YesYesNo
SIOLSimulation Input LinkINLINKYes YesYesNo
SVALSimulation ValueLONGNo YesYesNo
SIMSSimulation Mode SeverityMENU (menuAlarmSevr)Yes YesYesNo
SDLYSim. Mode Async DelayDOUBLEYes-1.0YesYesNo
SSCNSim. Mode ScanMENU (menuScan)Yes65535YesYesNo

Alarm Parameters

The possible alarm conditions for multi-bit binary input direct records are the SCAN and READ alarms. These alarms are not configurable by the user since they are always of MAJOR severity. No fields exist for the mbbi direct record to have state alarms.

Alarm Fields lists the fields related to alarms that are common to all record types.

Record Support

Record Support Routines


This routine initializes SIMM with the value of SIML if SIML type is CONSTANT link or creates a channel access link if SIML type is PV_LINK. SVAL is likewise initialized if SIOL is CONSTANT or PV_LINK.

This routine next checks to see that device support is available and a device support read routine is defined. If either does not exist, an error message is issued and processing is terminated.

Clears MASK and then sets the NOBT low order bits.

If device support includes init_record(), it is called.

refresh_bits is then called to refresh all the bit fields based on a hardware value.


See next section.

Record Processing

Routine process implements the following algorithm:

  1. Check to see that the appropriate device support module exists. If it doesn't, an error message is issued and processing is terminated with the PACT field still set to TRUE. This ensures that processes will no longer be called for this record. Thus error storms will not occur.
  2. readValue is called. See "Output Records" for information.
  3. If PACT has been changed to TRUE, the device support read routine has started but has not completed reading a new input value. In this case, the processing routine merely returns, leaving PACT TRUE.
  4. Convert.
    • status = read_mbbiDirect
    • PACT = TRUE
    • recGblGetTimeStamp() is called.
    • If status is 0, then determine VAL
      • Set rval = RVAL
      • Shift rval right SHFT bits
      • Set VAL = RVAL
    • If status is 1, return 0
    • If status is 2, set status = 0
  5. Check to see if monitors should be invoked.
    • Alarm monitors are invoked if the alarm status or severity has changed.
    • Archive and value change monitors are invoked if MLST is not equal to VAL.
    • Monitors for RVAL are checked whenever other monitors are invoked.
    • NSEV and NSTA are reset to 0.
  6. Scan forward link if necessary, set PACT FALSE, and return.

Device Support

Fields Of Interest To Device Support

Each input record must have an associated set of device support routines.

The primary responsibility of the device support routines is to obtain a new raw input value whenever read_mbbiDirect is called. The device support routines are primarily interested in the following fields:

FieldSummaryTypeDCT DefaultReadWriteCA PP
PACTRecord activeUCHARNo YesNoNo
NSEVNew Alarm SeverityMENU (menuAlarmSevr)No YesNoNo
NSTANew Alarm StatusMENU (menuAlarmStat)No YesNoNo
NOBTNumber of BitsSHORTYes YesNoNo
VALCurrent ValueLONGYes YesYesYes
INPInput SpecificationINLINKYes YesYesNo
RVALRaw ValueULONGNo YesYesYes
MASKHardware MaskULONGNo YesNoNo

Device Support Routines

Device support consists of the following routines:

long report(int level)

This optional routine is called by the IOC command dbior and is passed the report level that was requested by the user. It should print a report on the state of the device support to stdout. The level parameter may be used to output increasingly more detailed information at higher levels, or to select different types of information with different levels. Level zero should print no more than a small summary.

long init(int after)

This optional routine is called twice at IOC initialization time. The first call happens before any of the init_record() calls are made, with the integer parameter after set to 0. The second call happens after all of the init_record() calls have been made, with after set to 1.



This routine is optional. If provided, it is called by the record support init_record() routine. If it uses MASK, it should shift it as necessary and also give SHFT a value.


  get_ioint_info(int cmd,struct dbCommon *precord,IOSCANPVT *ppvt)

This routine is called by the ioEventScan system each time the record is added or deleted from an I/O event scan list. cmd has the value (0,1) if the record is being (added to, deleted from) an I/O event list. It must be provided for any device type that can use the ioEvent scanner.



This routine must provide a new input value. It returns the following values:

Device Support For Soft Records

Two soft device support modules, Soft Channel and Raw Soft Channel, are provided for multi-bit binary input direct records not related to actual hardware devices. The INP link type must be either CONSTANT, DB_LINK, or CA_LINK.

Soft Channel

For this module, read_mbbiDirect always returns a value of 2, which means that no conversion is performed.

If the INP link type is constant, then the constant value is stored into VAL by init_record(), and UDF is set to FALSE. VAL can be changed via dbPut requests. If the INP link type is PV_LINK, then dbCaAddInlink is called by init_record().

read_mbbiDirect calls recGblGetLinkValue to read the current value of VAL.

See "Input Records" for a further explanation.

If the return status of recGblGetLinkValue is zero, then read_mbbi sets UDF to FALSE. The status of recGblGetLinkValue is returned.

Raw Soft Channel

This module is like the previous except that values are read into RVAL, VAL is computed from RVAL, and read_mbbiDirect returns a value of 0. Thus the record processing routine will determine VAL in the normal way.